IGBT in Microwave Oven Systems

Microwave ovens are widely used in homes and offices for quickly heating food, and they have become an essential part of modern kitchens. In addition to reheating, microwave ovens are also used for cooking methods such as stewing, frying, baking, steaming, and fermenting. These appliances are typically designed as tabletop units or for installation above cooking ranges.

Microwave ovens heat food using the principle of dielectric heating through microwave radiation, usually at a frequency of 2.45 GHz. When microwaves pass through food, water, fats, and other molecules absorb the energy, which causes them to vibrate and generate heat. This process allows food to be heated more evenly and efficiently compared to conventional heating methods.

Earlier microwave oven designs used ferro-resonant circuits as part of the magnetron power supply. While these systems were relatively simple, they were also bulky and heavy due to the large low-frequency (50–60 Hz) step-up transformers required to generate high voltage.

With the introduction of IGBT technology, microwave oven power supplies have shifted toward high-frequency inverter-based designs. In these modern systems, IGBTs are used in the inverter circuit to efficiently control the high-voltage supply required by the magnetron.

In an IGBT-based microwave power supply, the anode voltage of the magnetron rises above 3500 volts when the IGBT switches on, enabling microwave generation. The output power of the magnetron can be precisely controlled by adjusting the IGBT switching on-time, allowing for more accurate and efficient cooking control.

The use of IGBT inverter circuits has significantly reduced the size and weight of microwave oven power supplies. Compared to traditional transformer-based designs, the transformer size and weight can be reduced by more than ten times, resulting in more compact, efficient, and lightweight microwave oven systems.